In recent years, the touch panel or touch screen have been developed and used widely. According to the different types of operation, the touch panel has resistive type, capacitive type, or optical type etc. Among them, the optical touch sensor can be configured on the touch panel such that the display screen can be used as an input area at the same time. The touch panel with the optical touch sensor includes a light detector and a light source that can emit light from the touch panel. When an object is placed on the touch panel, the light emitted by the light source is blocked at the region where the object is placed, wherein part of the light is reflected by the object and then enters the light detector. The touch panel is capable to realize the object existing in which part of the region by sensing the reflected light.
The optical touch panel is further integrated into a device which can scan object image. Therefore, the touch panel has touching and scanning function. However, in order to obtain a sufficiently clear object image, the scanning function requires a strong light source. Therefore, the light source of the touch panel must emit sufficient intensity.
In other words, the optical touch panel with scan function must have a greater light source comparing to the normal operation optical touch panel.
The touch panel function does not need a light source having high intensity. Therefore, the optical touch panel with scan function will waste a lot of electricity without scanning Furthermore, if the touch panel is configured on a portable electronic device, the electric power consumption of the touch panel case will affect the time that portable electronic device being used. In addition, if the light source of the touch panel emits visible light, the user will feel the strong light that is harsh to the eye and feel uncomfortable.